Generally, current display and projection technologies may include functionality to deploy, view and/or display three dimensional (“3D”) content. Recently, the increased demand for such functionality has driven the need for enhanced performance of projection technology. Projection systems typically use arc lamps, and in one example, xenon arc sources, for cinema projection systems, as the light source. Arc lamps have brightness which degrades over time due to electrode erosion, movement in the arc position relative to the collection optics, and particle buildup on the lamp walls.
More modern light sources employ coherent light sources, such as lasers, over incoherent arc lamps. The use of coherent or partially coherent sources can have advantages in display or illumination over standard incoherent sources (lamps) in that they can achieve higher brightness, better reliability, and larger color gamut. Lasers in particular provide a brighter light source with longer lifetimes as compared typical arc lamps.
Since lasers are coherent light sources, lasers suffer from the appearance of speckle when laser light is scattered from surfaces with roughness on the order of a wavelength. Speckle forms when coherent, but differently phased, portions of the reflected beam constructively and/or destructively add inside a single resolution spot of the detector, such as a human eye. In projection systems, speckle is due to interference of the light on a display screen or target that causes variations in intensity that can be seen by the observer or an instrument. The high contrast nature of the neighboring resolution spots disrupts the spatial continuity of the image. Thus, these typically high frequency intensity variations are very undesirable for display or imaging applications. Accordingly, it would be desirable in the art to have a technique for mitigating image speckle along the optical path, without significantly affecting image quality.